Move the source files into a new default directory.

build.gradle

@@ -1,14 +1,6 @@
 apply plugin: 'java'
 apply plugin: 'application'
 
-sourceSets {
-  main {
-    java {
-      srcDirs = ['src']
-    }
-  }
-}
-
 repositories {
   mavenCentral()
 }